Support for notebook v7

[danielhollas]

This ticket tracks changes needed to support Notebook v7 in the home app.

I did a brief test by opening all various notebook files by running jupyter notebook <app>.ipynb (i.e. I ran outside of Appmode), here's a list of problems I found (there might be more of course).

1. IPython object on the JS side does not exist, so the following code relying on it fails, for example

%%javascript
IPython.OutputArea.prototype._should_scroll = function(lines) {
    return false;
}

2. The Terminal app is broken
   

CC @unkcpz